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How to Manage Pests

UC Pest Management Guidelines

Dark powdery mildew lesions on pistachio shoot.


Powdery Mildew

Pathogens: Oidium sp.

(Reviewed 2/07, updated 2/09)

In this Guideline:


Powdery mildew starts as white powdery blotches on leaves, leaf stems, and fruit epicarp. Later in the season, these blotches turn brown to black and have a netted appearance. The blotches on fruit become russeted and cause the fruit to become misshapened. Multiple blotches like this cause leaves to yellow, then brown and die. Infected tissues may be distorted and misshapen. Similar symptoms can be found on rachises, fruit stems, petioles, underside of leaf blades, and young shoots.


The disease commonly occurs on the Trabonella cultivar. Red Aleppo is more susceptible than the Kerman cultivar.


The occurrence of powdery mildew on pistachio trees is uncommon and sporadic. No control measures are recommended.


[UC Peer Reviewed]

UC IPM Pest Management Guidelines: Pistachio
UC ANR Publication 3461
T. J. Michailides, Kearney Agricultural Center, Parlier
Acknowledgment for contributions to Diseases:
B. L. Teviotdale, Kearney Agricultural Center, Parlier

Statewide IPM Program, Agriculture and Natural Resources, University of California
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